Gasoline fuel compositions containing antiknock additive

ABSTRACT

A gasoline motor fuel possessing improved antiknock characteristics contains a minor amount of an aliphatic  beta -diketone and a minor amount of a chelate of cerium(IV) with a  beta -diketone.

This invention relates to gasoline motor fuels which have additives toenhance the antiknock properties of the gasoline.

In my U.S. Pat. No. 4,036,605, I describe the preparation of novelβ-diketone chelates of cerium(IV) and their use in motor gasoline asantiknock agents. I have now discovered that if sufficient aliphaticβ-diketone, which is itself inactive as an antiknock agent, is added tothis gasoline mixture containing the chelate of cerium(IV) with aβ-diketone, the antiknock characteristics of the gasoline areunexpectedly further elevated.

The useful β-diketone synergists are branched compounds which arerepresented by the general formula R₁ --CO--CH₂ --CO--R₂ where R₁ and R₂are alkyl radicals, with at least one being branched, having from 1 toabout 8 carbon atoms and a total of at least 5 carbon atoms. Preferredcompounds include 2,2-dimethyl-3,5-hexanedione;3,3-dimethyl-4,6-octanedione; 2,2,6-trimethyl-6-ethyl-3,5-octanedioneand 2,2,6,6-tetramethyl-3,5-heptanedione (thd). The most preferredcompounds are the most highly branched β-diketones.

The useful cerium(IV) chelates are prepared from β-diketones representedby the formula R₃ --CO--CH₂ --CO--R₄ where R₃ and R₄ are alkyl, aralkylor cycloalkyl radicals each containing from 1 to 12 carbon atoms with atotal of 5 to about 20 carbon atoms in said radicals. The preferredchelates of cerium(IV) contain the branched aliphatic β-diketones andthe most preferred chelates of cerium(IV) contain the highly branchedaliphatic β-diketones. A more detailed description of these cerium(IV)chelates and their preparation is found in U.S. Pat. No. 4,036,605,which disclosure is incorporated herein by reference.

The gasoline fuel composition desirably contains from about 0.01 toabout 5 g. per gallon of cerium as the cerium(IV) chelate and from about0.5 to about 20 g. per gallon of the β-diketone synergist for animproved antiknock rating and preferably contains from about 0.05 toabout 2 g. per gallon of cerium as the cerium(IV) chelate and from about2 to about 10 g. per gallon of the β-diketone.

EXAMPLES 1-16

A series of motor fuel compositions were tested for octane rating by themotor method (MON by ASTM D2700) and the research method (RON by ASTMD2699) using a clear commercial automotive gasoline having an MON of83.2 and an RON of 91.0. The cerium(IV) chelate that was used wastetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)cerium or Ce(thd)₄. Theresults of these experiments are set out in the following table in whicheach listed difference in octane numbers is based on consecutive,matched determinations with the β-diketone present and absent.

    ______________________________________                                             Ce                                                                       Ex.  g./gal. β-diketone                                                                             g./gal.                                                                             ΔMON                                                                           ΔRON                            ______________________________________                                        1    0       thd           4.0   0      0                                     2    0.5     thd           4.0   +0.6   +1.4                                  3    0.5     thd           4.0   +0.2   +1.1                                  4    1.0     thd           1.0   +0.3   +0.3                                  5    1.0     thd           2.0   +0.1   +0.6                                  6    1.0     thd           4.0   +0.3   +1.0                                  7    1.0     2,2-dimethyl-3,5-                                                                           4.0   +0.4   +0.2                                                hexanedione                                                     8    0.2     2-methyl-4,6- 2.0   0      +0.6                                                heptanedione                                                    9    1.0     3,5-heptanedione                                                                            4.0   0      -0.2                                  10   1.0     acetylacetone 4.0   -0.2   -0.8                                  11   1.0     trifluoroacetyl-                                                                            4.0   -0.4   +0.2                                                acetone                                                         12   1.0     1,3-cyclohexane-                                                                            4.0   0      -0.1                                                dione                                                           13   1.0     5,5-dimethyl-1,3-                                                                           4.0   0      -0.3                                                cyclohexanedione                                                14   1.0     2-acetylcyclo-                                                                              4.0   -0.6   -1.1                                                hexanone                                                        15   1.0     benzoylacetone                                                                              4.0   -0.2   0                                     16   1.0     dibenzoylmethane                                                                            4.0   -0.8   -1.1                                  ______________________________________                                    

It is noted from this table that the β-diketones of Examples 9-16undesirably lower one or both of the octane numbers of the fuelcomposition.

I claim:
 1. A gasoline motor fuel composition comprising a major amountof gasoline and a small amount, sufficient to improve the antiknockcharacteristics of the gasoline, of a free β-diketone and a chelate ofcerium(IV),a. said free β-diketone represented by the formula R₁ CO--CH₂--CO--R₂ where R₁ and R₂ are alkyl radicals with at least one beingbranched, each having from 1 to about 8 carbon atoms and having a totalof at least 5 carbon atoms, and b. said chelate of cerium(IV) is thetetrakis chelate with a β-diketone represented by the formula R₃--CO--CH₂ --CO--R₄ where R₃ and R₄ are alkyl, aralkyl or cycloalkylradicals, each containing from 1 to 12 carbon atoms and the sum of thecarbon atoms in said radicals is 5 to about
 20. 2. The gasoline motorfuel composition of claim 1 wherein the free β-diketone is present in anamount of about 2 to about 10 g. per gallon and the chelate ofcerium(IV) is present in an amount sufficient to incorporate about 0.05.to about 2 g. of cerium per gallon.
 3. The gasoline motor fuelcomposition of claims 1 or 2 wherein R₁, R₂, R₃, and R₄ are branchedchain alkyl groups.
 4. The gasoline motor fuel composition of claim 3wherein R₁, R₂, R₃, and R₄ are the same.
 5. The gasoline motor fuelcomposition of claims 1 or 2 wherein the β-diketone is2,2,6,6,tetramethyl-3,5-heptanedione.
 6. The gasoline motor fuelcomposition of claim 5 wherein the chelate of cerium(IV) istetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)cerium.